Current Enzooticity of Dirofilaria immitis and Angiostrongylus vasorum in Central and Southern Italy

<i>Dirofilaria immitis</i> and <i>Angiostrongylus vasorum</i> are major parasitic nematodes of dogs. Many environmental and phenological changes have recently modified their geographic patterns in many countries; thus, this study has updated the distribution of <i>D. immitis</i> and <i>A. vasorum</i> in dog populations of selected regions of Central and Southern Italy. Also, collateral data on other endoparasites affecting the study population have been collected. Blood and fecal samples collected from 2000 dogs were tested using Knott's test and copromicroscopy (i.e., Baermann's and fecal flotation tests), respectively. Binomial logistic regression was performed to evaluate statistically significant associations between positivity for <i>D. immitis</i> and/or <i>A. vasorum</i> and potential risk factors. Overall, 35 (1.7%) and 62 (3.1%) dogs were positive for microfilariae of <i>D. immitis</i> and first stage larvae (L1) of <i>A. vasorum</i>, respectively, while 3 (0.1%) were co-infected by both nematodes. Microfilariae of <i>Dirofilaria repens</i> were found in 148 (7.4%) dogs, while at the flotation, eggs of Ancylostomatidae, <i>Trichuris vulpis,</i> and ascarids were found in the feces of 323 (16.5%), 249 (12.4%), and 172 (8.6%), dogs, respectively. Overall, 217 (10.8%) and 44 (2.2%) dogs were positive for eggs of <i>Capillaria aerophila</i> and <i>Capillaria boehmi</i>. The presence of cardiorespiratory clinical signs or non-specific signs, history of travel, and an age of >4 years old were significantly associated with positivity for <i>D. immitis</i>, while <i>A. vasorum</i> was significantly recorded in dogs with cardiorespiratory signs, or with a history of mollusk ingestion or permanent outdoor housing. These results confirm that <i>D. immitis</i> is enzootic in the investigated regions of Central and Southern Italy, even where it was rare/undetected until recently. Indeed, although some dogs positive for <i>D. immitis</i> had a history of travel in enzootic areas, the majority of them were never moved, indicating that they acquired the parasite in the region where they live. Additionally, <i>A. vasorum</i> is stably enzootic in the study areas, as also are other extraintestinal nematodes (i.e., <i>D. repens</i> and <i>C. aerophila</i>) that are more frequently detected today than in the past. A high level of vigilance and routine parasitological screening are necessary, considering the high prevalence of intestinal parasites in owned dogs that are also co-infected by respiratory parasites. The implementation of chemoprevention against <i>D. immitis</i> in dogs living in the examined area should be encouraged.